#pragma once

#include <optional>
#include <unordered_map>

#include <Core/Block.h>
#include <Formats/FormatSettings.h>
#include <Formats/IRowInputStream.h>


namespace DB
{

class ReadBuffer;


/** A stream to input data in tsv format.
  */
class TabSeparatedRowInputStream : public IRowInputStream
{
public:
    /** with_names - the first line is the header with the names of the columns
      * with_types - on the next line header with type names
      */
    TabSeparatedRowInputStream(
        ReadBuffer & istr_, const Block & header_, bool with_names_, bool with_types_, const FormatSettings & format_settings);

    bool read(MutableColumns & columns, RowReadExtension & ext) override;
    void readPrefix() override;
    bool allowSyncAfterError() const override { return true; }
    void syncAfterError() override;

    std::string getDiagnosticInfo() override;

private:
    ReadBuffer & istr;
    Block header;
    bool with_names;
    bool with_types;
    const FormatSettings format_settings;
    DataTypes data_types;

    using IndexesMap = std::unordered_map<String, size_t>;
    IndexesMap column_indexes_by_names;

    using OptionalIndexes = std::vector<std::optional<size_t>>;
    OptionalIndexes column_indexes_for_input_fields;

    std::vector<UInt8> read_columns;
    std::vector<size_t> columns_to_fill_with_default_values;

    void addInputColumn(const String & column_name);
    void setupAllColumnsByTableSchema();
    void fillUnreadColumnsWithDefaults(MutableColumns & columns, RowReadExtension& ext);

    /// For convenient diagnostics in case of an error.

    size_t row_num = 0;

    /// How many bytes were read, not counting those still in the buffer.
    size_t bytes_read_at_start_of_buffer_on_current_row = 0;
    size_t bytes_read_at_start_of_buffer_on_prev_row = 0;

    char * pos_of_current_row = nullptr;
    char * pos_of_prev_row = nullptr;

    void updateDiagnosticInfo();

    bool parseRowAndPrintDiagnosticInfo(MutableColumns & columns,
        WriteBuffer & out, size_t max_length_of_column_name, size_t max_length_of_data_type_name);
};

}